Test House

All of our test house services (thermal vacuum chambers, outgassing test facility and vacuum UV exposure chambers) have been incredibly busy this year. We received delivery of our new vacuum chamber TVAC#2 in the last few days of 2017 and by July 2018 the system was put to work for flight hardware bakeouts and several thermal vacuum cycling tests. TVAC#1 is currently down for maintenance and should be back online beginning of 2019.

In June we also supported the 2018 edition of 'Aerospace Test & Validation' with various images from our test house equipment and solar simulator products. ​This is a new publication from the publishers of the Test House Directory focused specifically on the Aerospace industry. ​You can read the digital version here.

Our outgassing facility has been extremely busy also, with our facility taking part in the ESA inter-laboratory ECSS-Q-ST-70-02C outgassing quantification study in July this year.

In 2019 we will be expanding our test facilities to include FTIR capabilities. Check our news page or follow us on Twitter for announcements on this.

Aerospace Test & Validation - 2018 featuring TS-Space Systems cover

Unisim Compact Solar Simulator - close match solar simulator for small research applications

Solar Simulators

Our solar simulator builds have also been consistent throughout the year, with several of our smaller Unisim Compact solar simulator systems shipping out. We have also had some larger system builds with custom specifications. We are also looking to at a short R&D project for our Unisim N-Zone simulators which will push their capabilities into larger working areas. The materials for this have just been delivered and will be scheduled when we start 2019.

Christmas Closing

We would like to thank all of our customers, old and new, for continuing to select our products and services in 2018 and we look forward to working with you in the future. From all of us at TS-Space Systems, we'd like to wish you a very Merry Christmas, a Happy New Year for 2019!

Last day opening 2018: Friday December 21stFirst day opening 2019: Wednesday January 2nd

Solar Simulators

We have been busy in the second half of 2018 with, amongst other projects, several large simulator builds. Our Unisim Compact range of small, close-match solar simulators continue to also prove popular and our last system in stock has just shipped to the University of New South Wales.

We are continuing to work on the application of LED technology to our close-match simulators and have some interesting R&D work coming up in 2019 which will take our N-Zone solar simulator design to large area applications.

TVAC Chambers

2018 has been very busy for our thermal vacuum chambers TVAC#1 and TVAC#2 as we have conducted bakeout and TVAC cycling work for a range of customers, including quite a lot of components for the ESA Solar Orbiter mission.

​We are currently designing a full IR heat shroud for TVAC#2 to be fitted in 2019. We had hoped to complete in late 2018 but demand for the chamber has meant maintenance time has been limited.

FTIR Analysis

We are excited to announce that we will be expanding our lab capabilities to include FTIR analysis via transmission and ATR in early 2019. This facility will primarily be used for analysing molecular witness plates for contamination control during vacuum bakeouts. However, we will also be offering FTIR analysis of condensables collected from our standard outgassing test. There will be further announcements via this news page and our main test facilities page when this becomes available.

We are making our in-house Unisim Compact available for demonstration and testing. You are also welcome, without any obligation, to use our house Compact for a half-day to measure any of the cells on which you are currently working.​The Unisim Compact demonstration covers all of the technical aspects of our close-match solar simulators as well as:

If you would like to book a demonstration and/or measurement session please contact us.

We have updated the Unisim Compact solar simulator and will be uploading the details of the new system at the end of the month.

For existing Unisim Compact solar simulator customers the new enclosure systems are available free of charge and will be dispatched shortly. If we have not already contacted you, please email us﻿ and we will arrange an enclosure kit for you.

TS-Space Systems is proud to have supplied a Unisim Solar Simulator to NEC Space Technologies, LTD. a world leader in the manufacture and testing of satellite equipment.

The Unisim close match solar simulator provides a world leading close spectral match to the standard AM0 spectrum via multiple discrete wavebands which is vital for accurately characterising the multijunction solar cells used for space applications.

"We are very pleased to work with NEC Space Technologies LTD again", said Dr Bill Williams, Director at TS-Space Systems, "We are proud to add NEC Space Technologies LTD. to the long list of leading PV research and manufacturing groups who have selected our solar simulators for their work".

We are busy finishing several large simulator builds at the moment, but we are still planning new additions to our products and services for 2016.

We have new LED boost options for our Unisim Compact solar simulators and we will be launching our in-house simulator demo service in 2016. Customers will be able to book a day on our in-house Unisim Compact solar simulator and try it out for themselves. Tea and biscuits included!

2015 has been an incredibly busy year for our outgassing rig. If you are interested in outgassing or any of our in-house test services, the sooner you contact us the more likely we are to fit you in to our test schedule.

We value product support very highly at TS-Space Systems which is why we offer extensive support via phone and email for the full lifetime of every TS-Space Systems product. Training is also provided at our premises where customers can take advantage of one-on-one tuition with the product designers to learn how to operate and maintain their solar simulators and other tools.

With our solar simulators and other products being used across the world we aim to provide fast and effective product support. To help in this, we have now added a support forum to our website where we intend to build a repository of information that can provide further support, answer questions if you are having problems or even help you out if you have inherited an old TS-Space Systems solar simulator or product. We have also included forums for our test services and we have already started an FAQ for our outgassing test services.

If you have a question or information you'd like to see included in an FAQ, post it in the relevant section and we'll add it in.

The ASTM standard for solar simulators states that: "A solar simulator (also artificial sun) is a device that provides illumination approximating natural sunlight. The purpose of the solar simulator is to provide a controllable indoor test facility under laboratory conditions, used for the testing of solar cells, sun screen, plastics, and other materials and devices." [1] and that: "A solar simulator usually consists of three major components: (1) light source(s) and associated power supply; (2) any optics and filters required to modify the output beam to meet the classification requirements" [1] Thus we need to select a light source that approximates the solar spectrum we want to simulate, be it AM0 for space applications of AM1.5 for terrestrial, and appropriate power supply. We also need to be able to manipulate the beam via an optical system such that the spectrum and spatial uniformity of irradiance can be optimised for the required application. Light SourcesThere are four commonly used light sources used in solar simulators:

Xenon Arc Lamps - These have been commonly used in most simulators since the very first 1960's designs due to the raw output having a fairly approximate match to the AM0 spectrum. There are, however, large infra-red "spikes" which must be attenuated to achieve a close spectral match. Even so, a single source solar simulator consisting of an IR filtered xenon arc source will provide a crude match to AM0/AM1.5, which is acceptable if you are testing single-junction devices or biological tests where an exact spectral match is not necessary. They are expensive compared to other arc sources, primarily due to the increasing demand for a limited global supply of xenon.

Metal Halide Arc Lamps (HMI) - Commonly used in film and television lighting where a close match to daylight is required along with a high temporal stability for filming, metal halide arc lamps provide an alternative to xenon which are more stable, give better temporal stability, are low-pressure, easier to maintain and cheaper. The spectral perturbations in the infra-red are much reduced from xenon, meaning they are excellent basis for both Class "A" and advanced solar simulators (see relevant section above). For reference, an unfiltered metal halide arc lamp will produce a B class spectral match.

Light Emitting Diodes (LED) - Recent advances in LED technology for the general domestic market has made high-power LED's commonly available. The advantages for solar simulators are obvious as they have a lower energy consumption and longer lifetime than arc lamps. There are limitations, however. They are only available in discrete wavelengths i.e. a continuous spectrum requires a cluster of LED's operating at different wavelengths which produces a crude spectral match. More importantly, the commonly available wavelength LED's do not cover the full spectrum required for more advanced, multi-junction devices which have a spectral response past 1000nm.

Quartz Tungsten Halogen Lamps (QTH) - These provide an excellent black-body match in the infra-red but very poor across the visible range. As such they are more commonly used in more advanced multi-source solar simulators. See our previous post for more information on advanced solar simulators.

Power Supplies These are typically dictated by the light source used. For example, arc lamp power supplies are typically highly complex devices that have to manage a high voltage ignition stage in order to establish the arc. QTH lamps will require a comparatively more simple DC source with a compatible power output.

Optics The optical layout of a solar simulator varies greatly depending on a multitude of variables including: the type and number of light sources used, the area of illumination generated, the spectral output generated etc. For basic solar simulators there are perhaps greater areas of commonality between manufacturers: a parabolic reflector, mixing mirror, IR clipping filter and 90 degree "down" mirror are generally found in single source xenon Class "A" systems. Generally, major concerns for the optical system of a solar system (beyond achieving its required classification) is the ease of use/adjustment and maintenance. If a specific vertical or horizontal beam orientation is required then this should also be considered.

With the advent of cells with more than four junctions, the basic design of the TS-Space Systems Unisim range reached its sensible limit. To provide for five and more junctions, the N-zone solar simulator was introduced. This is very sophisticated, and can be used to analyse cells with up to twelve junctions with-out the adjustment of any one junction affecting the other.A simplified version of this simulator is now offered. This is based on our standard, spectrally close-matched simulators, but uses LED boost zones in place of the traditional arc and tungsten lamps, up to 1100nm. These are much more compact than our simulator zones, are extremely stable and perform well within the international standards for spatial uniformity of +/-2%.

The basic technique, assuming that illumination levels above and below AM0 are required, is to reduce the overall level of illumination of the simulator so as to be, say, 10% below AM0, but maintaining the AM0 spectral distribution (Figure 1).

Selected LED's are then used to provide the correct illumination for each junction at AM0 (Figure 2). By varying the output of these LED's, the current in any selected junction may be increased or decreased as required. In this way, any junction may be investigated independently of any other junction. Please note that alternative LED wavelengths to the ones demonstrated here are available.

The LED banks can be retrospectively installed in existing Unisim solar simulators or included at the point of manufacture. They are computer controlled using dedicated rack-mount power supply units which control the current limit and temperature of the individual LED's to automatically prevent any drift in wavelength. Custom software allows for computercontrol of an individual LED as well as groups of LED's with the same wavelength. LED output configurations of the simulator can be saved and recalled.

The software automatically detects the LED units installed at start-up which allows the user to replace individual LED's or even install an alternative wavelength LED with minimal disruption to the control system. Thus any later changes to simulator wavelength requirements can be accommodated with minimal cost and downtime.

While most basic solar simulators use a single xenon lamp as their light source, advanced solar simulators commonly use multiple light sources (referred to as 'multi-source') in order to achieve a close spectral match to the reference spectrum. This is generally done by filtering and merging the output of two types of source, usually an arc source (metal halide or xenon) for the visible and a QTH source for the NIR-LWIR ranges. The term 'close-match' to describe a solar simulator that attempted to move beyond a single-source design and accurately reproduce the solar reference spectrum was first used in 1997 by Dr Williams from 'TS-Space Systems LTD' when the results from the first ever close-match solar simulator were presented. The research compared the results of testing multi-junction solar cells using a close-match spectrum to the results from using another, basic solar simulator and showed measurement variations of up to 20% in some cases.

The importance of a good spectral match or 'close-match' solar simulator for accurately measuring and investigating multi-junction solar cells was clear and has since been thoroughly demonstrated in the research literature:"The photovoltaic characterization of triple-junction InGaP2/GaAs/Ge solar cells is presented. Measurements made using a single light source solar simulator are compared with other measurements made using a multi-light source solar simulator that provides a close match to the air mass zero (AM0) solar spectrum. The output spectrum of the solar simulators has been measured, and two methods for calibrating the simulator output intensity haven been employed. The spectral response of the solar cells has been characterized through quantum efficiency measurements. These data are analyzed to determine the effect of the simulator spectrum on the measured photovoltaic response, and in particular, areas where spectral mismatch between the simulator and AM0 can lead to inaccurate performance predictions are highlighted."[3]

Figure from [2] comparing a basic spectral match and the new 'close-match' solar simulator presented in [1]. The deviation at 2200nm onwards is due to the spectrometer calibration.